Seventeen high-profile association CEOs have announced departures year to date—more than were announced in 2016 and 2017 combined, according to CEO Update research.

But executive recruiters don’t see a pattern; instead they see different factors coming together simultaneously: retirements, politics, political ambitions, desire to give back to community, and the inevitable situations that turned south.

“There’s a confluence of events that has precipitated a number of the more prominent trade association executives retiring and moving on,” said Nels Olson, vice chairman at Korn Ferry.